A total of 199 confirmed and 14 probable cases of botulism were reported to CDC in 2015. Among confirmed cases, infant botulism accounted for 141 (71%) cases, foodborne botulism for 39 (20%) cases, wound botulism for 15 (8%) cases, and botulism of unknown or other transmission category for 4 (2%) cases (Table 1). Among probable cases, foodborne botulism accounted for 6 (43%) cases and wound botulism for 8 (57%) cases.
The 141 cases of infant botulism were reported from 33 states and the District of Columbia. The median age of patients was 2.7 months with a range of 0 – 10 months; 70 (50%) were girls. Toxin type A accounted for 60 (43%), toxin type B accounted for 79 (56%), and toxin type Bf accounted for 2 (1%). No deaths were reported.
The 39 cases of confirmed foodborne botulism were reported from 7 states (Figure 1). The median age of patients was 59 years with a range of 9 – 92 years; 25 (64%) were women. There were 5 outbreaks (events with two or more cases) accounting for 37 confirmed cases. One outbreak was associated with home-canned potatoes in a potato salad served at a church potluck (27 cases),† one was associated with fermented seal flipper (4 cases), and one was associated with beets roasted in aluminum foil and kept at room temperature for several days then made into a soup (2 cases). In addition, there were two outbreaks of two cases each living in the same household or facility in which the foodborne source was unknown (Table 2a). Toxin type A accounted for 34 (87%), and toxin type E accounted for 5 (13%). One death was reported.
The 6 cases of probable foodborne botulism (clinically compatible illness, not laboratory-confirmed, with an epidemiologic link to a suspect food) were reported from 3 states. The median age of patients was 53 years with a range of 23 – 73 years; 3 (50%) were women. No deaths were reported. Seal oil was the suspected food source for 2 of the 6 probable cases (Table 2b).
There were 15 cases of confirmed wound botulism reported from 5 states. The median age of patients was 49 years with a range of 12 – 61 years; 2 (13%) were women. Toxin type A accounted for 14 (93%), and toxin type B accounted for 1 (7%). Fourteen (93%) were people who inject drugs (PWID). One death was reported.
The 8 cases of probable wound botulism (clinically compatible case who has no suspected exposure to contaminated food and who has a history in the 2 weeks before illness began of either a fresh wound or injection drug use) were reported from 3 states. The median age of patients was 59 years with a range of 28 – 78 years; 1 (12%) was a woman. All 8 were PWID. No deaths were reported.
The 4 confirmed botulism cases of unknown etiology were reported from 3 states. The median age of patients was 47 years with a range of 27 – 71 years; 1 (25%) was a woman. Toxin type A accounted for all 4. No definitive route of transmission was identified for these cases. Two cases were suspected to be adult intestinal colonization, a rare form of botulism thought to have a similar mechanism as infant botulism. The other two cases did not consume a suspect food, have any wounds, or have any known risk factors for adult intestinal colonization. How these persons were exposed to botulinum toxin is unknown. One patient developed botulism in 2015 and died in 2016 during a prolonged hospitalization.